Increase BURST_LEN to 47 (48 beats) to cover 192-byte C reads in one burst

sdk/software/examples/asm/dma.c

@@ -18,7 +18,7 @@ void dma_start_transfer(int ch_id, uint32_t src, uint32_t dst, uint32_t bytes, u
     // 置 Burst 属性并触发传输
     // AXI SIZE: 2 (代表 2^2 = 4 Bytes，与 32-bit 数据线匹配)
     // AXI LEN: 15 (代表 16 beats 突发传输，最高效)
-    uint32_t ctrl_val = CTRL_BURST_SIZE(2) | CTRL_BURST_LEN(15);
+    uint32_t ctrl_val = CTRL_BURST_SIZE(2) | CTRL_BURST_LEN(47);
     
     // 写入 CTRL 并拉高 Bit 0 (Start)
     ch->CTRL = ctrl_val | CTRL_START_BIT;